See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/314843576 The Namib-Thar Desert Disjunction in Dactyliandra (Cucurbitaceae) is the Result of a Recent Introduction to India Article in Systematic Botany · March 2017 DOI: 10.1600/036364417X694548 CITATION READS 1 281 4 authors, including: Arun Pandey Hanno Schaefer University of Delhi Technische Universität München 74 PUBLICATIONS 271 CITATIONS 138 PUBLICATIONS 2,708 CITATIONS SEE PROFILE SEE PROFILE Some of the authors of this publication are also working on these related projects: Plants & Pollinators View project Systematics of Alysicarpus, Crotalaria and Indigofera (Fabaceae) View project All content following this page was uploaded by Hanno Schaefer on 13 March 2017. The user has requested enhancement of the downloaded file. Systematic Botany (2017), 42(1): pp. 63–72 © Copyright 2017 by the American Society of Plant Taxonomists DOI 10.1600/036364417X694548 Date of publication March 1, 2017 The Namib-Thar Desert Disjunction in Dactyliandra (Cucurbitaceae) is the Result of a Recent Introduction to India Katharina Lindner,1 Yue Hu,1 Arun K. Pandey,2 and Hanno Schaefer1,3 1Plant Biodiversity Research, Department Ecology and Ecosystem Management, Technical University of Munich (TUM), Emil-Ramann Str. 2, D-86354 Freising, Germany. 2Department of Botany, University of Delhi, Delhi-110 007, India. 3Author for correspondence ([email protected]) Communicating Editor: Chrissen E. C. Gemmill Abstract—Depending on taxonomic concept, the genus Dactyliandra (Cucurbitaceae) comprises up to four species: two from Southwest Africa, D. luederitziana (Namibia) and D. welwitschii (Angola), and two very locally distributed and poorly known taxa from Northeast Africa, D. nigrescens and D. stefaninii. In addition to these African populations, D. welwitschii was also reported as a possibly native species from the Thar desert of Northwestern India and Pakistan ca. 8,000 km away from the Namib range. A phylogenetic analysis of plastid and nuclear ribosomal ITS DNA sequences including all Dactyliandra species and D. welwitschii from the Thar desert revealed that this striking disjunction is of very recent origin. Dactyliandra is monophyletic only after exclusion of the East African taxa, which are best placed in Trochomeria. The species Dactyliandra welwitschii is monophyletic and includes the Indian plants, which group with a sample from an Angolan population. We hypothesize that this unexpected connection is a result of man-mediated introduction to India from Africa perhaps in the times of the slave trade. The new combinations Blastania lucorum and Trochomeria nigrescens are published here. Keywords—Blastania, continental tracks, molecular clock, Saharo-Sindian desert belt, Siddi, Trochomeria. The genus Dactyliandra Hook.f. was originally described by Africa. A further East African species, D. stefaninii (Chiov.) the British botanist Joseph D. Hooker in 1871 from material C. Jeffrey, also remained more or less unnoticed. Dactyliandra collected in Angola, southwestern Africa (Hooker 1871). The stefaninii had been described by Chiovenda as a species of species was described as D. welwitschii Hook.f. to honor the Coccinia Wight & Arn. (Chiovenda 1917), it was later trans- Austrian explorer and botanist Friedrich Welwitsch (1806– ferred to Trochomeria Hook.f. by Jeffrey in 1962 and finally 1872) who had collected the type material. Further fieldwork moved to Dactyliandra in 1985 (Jeffrey 1962, 1985). These East revealed that its distribution is restricted to the Namib region African plants reduced the extreme disjunction in the genus of Angola and adjacent Namibia. The Namibian plants (Fig. 1) but at the same time called into question the species circum- seemed to be morphologically slightly different (3-lobed leaves scriptions in Dactyliandra, with the populations of the two instead of 5- to 7-lobed leaves) when Cogniaux studied the extreme ends of the range being attributed to the same spe- very limited number of herbarium collections available to him cies and two different species living more or less in sympatry and therefore described them as a second species, D. luederitziana in between (Fig. 2). Cogn. (Cogniaux 1916). This concept, however, was not Family-wide phylogenetic analyses placed D. welwitschii accepted and the following authors treated all Southwest in the tribe Benincaseae in a well-supported clade together African plants as one single species D. welwitschii (e.g. Meeuse with representatives of the genera Trochomeria, Blastania 1962, Gibbs Russell et al. 1987). Kotschy & Peyr. (syn. Ctenolepis Hook.f.), and Benincasa Savi It was a big surprise when almost a century after Welwitsch’s (Schaefer et al. 2009; Schaefer and Renner 2011). However, discovery, the Indian botanist M. Bhandari found Dactyliandra these analyses only included one representative per genus, plants morphologically matching D. welwitschii in Rajasthan so could not elucidate the evolution and historical biogeog- about 8,000 km away from the species’spreviouslyknown raphy within Dactyliandra. distribution range (Bhandari and Singh 1964; Fig. 2). In Here, we use a comprehensive sample of Dactyliandra and Rajasthan, the species was reported to be locally common as a presumed relatives to test in a phylogenetic framework climber over Capparis L. bushes and in hedges but Bhandari & the hypotheses that 1) Dactyliandra is monophyletic, and Singh (1964) also suggested that it might have been 2) populations in India/Pakistan, East Africa, and Southwest overlooked or confused with the similar looking Blastania Africa are three genetically and morphologically distinct enti- garcini (L.) Cogn. (syn. Ctenolepis garcini (L.) C. B. Clarke) and ties and remainders of a former widespread ancestor, whose might be more widespread. Later, the species was indeed also range covered the entire Saharo-Sindian desert belt region. found in the Kirthar Range on the Pakistani side of the border (Khatoon 2006). This suggested that the total Thar region pop- Materials and Methods ulation might be bigger and cover a relatively large range, which could indicate an indigenous status. The case was Taxon Sampling — For the molecular phylogenetic analyses, we included widely cited as an example of an extreme disjunction and even seven accessions of Trochomeria and 15 accessions representing the three or used by panbiogeographers as evidence for “tracks” between four Dactyliandra species: ten specimens of D. welwitschii/D. luederitziana, four of them from Namibia, and three from India and Angola respectively, continents (Craw et al. 1999). However, doubts about its native and we downloaded sequences for an additional Namibian sample from status remained and a human-mediated introduction to the GenBank. For D. stefaninii and D. nigrescens, we sequenced two specimens Thar region could not be excluded. each, all of East African origin. For the presumed sister genus Trochomeria, Less attention was given to an additional species of we included the following four species in our phylogenetic analyses: T. debilis Benth. & Hook.f. (one specimen), T. macrocarpa Harv. (three speci- Dactyliandra, D. nigrescens C. Jeffrey (Jeffrey 1965), which was mens), T. polymorpha Cogn. (two specimens), and T. sagittata Benth. & Hook.f. described at the same time from Eastern Africa, roughly in (one specimen). Finally, we added five samples of the genera Blastania and the middle of the route from Northern India to Southwestern Benincasa as outgroups based on the results of earlier family-wide analyses 63 64 SYSTEMATIC BOTANY [Volume 42 Fig. 1. Dactyliandra welwitschii Namibia, Farm Kyffhauser. A. Habit; note simple tendrils and 5-lobed leaf. B. Male flower and ciliate bracts; note glandular hairy petal surface. C. Unripe green fruits. D. Mature pink fruits. Scale bars = 5 mm. (Photographer A. Dreyer). (Schaefer et al. 2009, Schaefer and Renner 2011). Appendix 1 provides (Stocks) A. Meeuse, 26 of Trochomeria macrocarpa (Sond.) Hook.f., five of voucher information and GenBank numbers for all included sequences. T. polymorpha Cogn., and one of T. debilis Hook.f. (for specimen details For the morphological comparisons and development of the determina- see appendix). Further specimens from the herbarium of the Botanische tion key, we studied 115 specimens at the herbarium of Royal Botanical Staatssammlung Munich (M) were studied to see if morphological Gardens Kew (K): for the genus Dactylindra, we studied 52 specimens of variation was within the range of variation of the vouchers in K. All D. welwitschii/D. luederitziana, eight specimens of D. stefaninii, and eight measurements were taken from dry herbarium specimens. specimens of D. nigrescens;15specimensofBlastania cerasiformis Scans of type material of all Dactyliandra species can be accessed in the Global plants database of JSTOR using the following links: http://plants.jstor.org/compilation/Dactyliandra.welwitschii http://plants.jstor.org/compilation/Dactyliandra.nigrescens http://plants.jstor.org/compilation/Dactyliandra.stefaninii DNA Extraction and PCR — DNA extraction followed standard pro- cedures described in Kocyan et al. (2007). Polymerase chain reactions (PCR) were performed using two different premixed reaction kits: a) the Nova Taq™ PCR Master Mix (Merck) and b) the KAPA2G™ Fast 2x ReadyMix (Kapa Biosystems Inc.). We amplified the nuclear ribosomal internal transcribed spacer (ITS) region using the primers of Douzery et al. (1999), and from the plastid